1. Field of the Invention
This invention relates to a stapler apparatus having a needle staple mechanism for feeding staple blanks continuously formed in succession to a driving-in station.
2. Related Background Art
Heretofore, a staple blank feeding apparatus as shown in FIG. 8 of the accompanying drawings wherein staples are fed one by one has been prepared for the next staple blank feeding by moving a feeding pawl 37 in the direction opposite to the feeding direction of needles 45 in the normal state as shown in FIG. 11 of the accompanying drawings. While the leading staple blank 46 bent as shown in FIG. 9(b) of the accompanying drawings is preventing the backward movement of the staple blanks. This will hereinafter be described in detail with reference to FIG. 11. The leading staple blank 46 has its central portion held by a holding block 35. At this time, the leading staple blank 46 is not yet bent, but is in its state shown in FIG. 9(a) of the accompanying drawings. Subsequently, by pushing a roller 23 downwardly, a plate spring member 25 and a bending block 41 are moved downwardly, and the bending block 41 strikes against the opposite ends of the leading staple blank 46 and bends it as shown in FIG. 9(b). When the roller 23 is further pushed in, the projected portion 47 of the bending block 41 distorts a staple blank feeding member 36 as indicated by dotted line. Thereupon, the staple blank feeding pawl 37 moves in the direction opposite to the staple blank feeding direction. However, by this time, the leading staple blank 46 has already been bent as shown in FIG. 9(b) and is caught by a cutting member 40. Therefore, the staple blanks 45 do not go back and only the feeding pawl 37 moves in the opposite direction and can become ready for the next staple blank feeding. Thereafter, when the roller 23 is further moved downwardly, the block pushing pawl 42 of the plate spring member 25 comes off the bending block 41 and only the fore end 43 of the plate spring comes down. Then, the fore end 43 of the plate spring cooperates with a cutting member 40 to cut the leading staple blank 46 off the succeeding staple blank 45 while pushing aside the holding block 35 into the state indicated by dot-and-dash line. The leading staple blank 46 is driven into a bundle of paper and sumultaneously therewith, it bends the leading staple blank as shown in FIG. 9(c) of the accompanying drawings, thereby binding the bundle of paper. When the leading needle has been completely driven into the bundle of paper, the roller 23 is returned upwardly and the projected portion 47 comes off the staple blank feeding member 36, and the feeding pawl 37 returns to its original position, i.e., the position indicated by solid line. At this time, the staple blanks 45 move forward. By the above-described operation, staple blank feeding is reliably effected in the normal state.
However, it is often the case that the fore end of the staple blanks 45 does not reach the bending station B when a staple blank cartridge 28 has been mounted. The leading staple blank 46 is not bent and is not caught by the cutting member 40 and therefore, the staple blanks only reciprocally move with the reciprocal movement of the feeding pawl 37 and do not move forward. Thus, the needles do not arrive at the bending station B.